The Nature of Waves
A wave is a disturbance that transfers energy from one place to another without transferring matter.
Types of Waves
Transverse Wave: The particles of the medium oscillate perpendicular to the direction of wave propagation. Examples include light waves and waves on a string.
Longitudinal Wave: The particles of the a medium oscillate parallel to the direction of wave propagation. It consists of areas of compression and rarefaction. Examples include sound waves and a pushed slinky.
Wave Properties
Wavelength (λ, lambda): The spatial period of the wave – the distance over which the wave's shape repeats.
Frequency (f): The number of complete oscillations that pass a point per unit of time. Measured in Hertz (Hz).
Amplitude: The maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position.
Wave Speed (v): How fast the wave propagates. It is related to frequency and wavelength by the fundamental wave equation:
v = fλ
Wave Phenomena
Interference: Occurs when two or more waves meet.
Constructive Interference: The waves add up to create a wave with a larger amplitude.
Destructive Interference: The waves cancel each other out to create a wave with a smaller amplitude.
Diffraction: The bending of waves as they pass around an obstacle or through an opening (aperture).
Doppler Effect: The change in frequency of a wave in relation to an observer who is moving relative to the wave source. If the source and observer are moving closer, the perceived frequency is higher (e.g., a high-pitched ambulance siren approaching). If they are moving apart, the perceived frequency is lower (a low-pitched siren moving away).
Sound Waves
Sound is a mechanical, longitudinal wave.
It is mechanical because it requires a medium (solid, liquid, or gas) to travel through; it cannot travel in a vacuum.
It is longitudinal because it consists of compressions and rarefactions of the particles of the medium.
The pitch of a sound is determined by its frequency.
The loudness of a sound is determined by its amplitude.